import pandas as pd
df = pd.DataFrame({'商品':['苹果','香蕉','梨'],
                   '单价(元)':[5,5,4],
                   '销量(kg)':[100,None,None],
                   '库存(kg)':[50,None,70]})
print('原始数据:\n',df)
print('检查缺失值:\n',df.isnull())
print('检查非缺失值:\n',df.notnull())
print('统计每列缺失值的个数:\n',df.isnull().sum())


import pandas as pd
df=pd.DataFrame({'商品':['苹果','香蕉','梨'],
                 '单价(元)':[5,5,4],
                 '销量(kg)':[100,None,None],
                 '库存(kg)':[50,None,70]})
print('原始数据:\n',df)
print('删除包含缺失值的行:\n',df.dropna())
print('删除包含缺失值的列:\n',df.dropna(axis=1))
print('删除少于3个非缺失值的行:\n',df.dropna(thresh=3))
print('删除库存列包含缺失值的行:\n',df.dropna(subset=['库存(kg)']))